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  <div class="titlepage"><div><div><h1 style="clear: both"><code>is_error_code_available&lt;T&gt;</code></h1></div></div></div>
  <p><code>::value</code> is true if an error code can be constructed from a <code>T</code> e.g. if there exists an ADL discovered free function <code>make_error_code(T)</code>.
<code>::type</code> is the type that would result if <code>::value</code> is true, else <code>void</code>.</p>

<p><em>Overridable</em>: By template specialisation into the <code>trait</code> namespace.</p>

<p><em>Default</em>: True if <code>T</code> is an error code, else to metaprogramming which performs the ADL discovery of <code>make_error_code(T)</code>. Note that the STL defines multiple overloads of an ADL discovered free function 
<a href="https://en.cppreference.com/mwiki/index.php?title=Special%3ASearch&search=make_error_code" class="api-reference" target="_blank"><i class="fa fa-book" aria-hidden="true"></i> <code>std::make_error_code(T)</code></a>
 for its error enumerations, as does Boost.System for the Boost error enumerations. Thus this trait will pick up those free functions for those error types.</p>

<p><em>Namespace</em>: <code>BOOST_OUTCOME_V2_NAMESPACE::trait</code></p>

<p><em>Header</em>: <code>&lt;boost/outcome/trait.hpp&gt;</code></p>

<p><em>Variable alias</em>: <code>is_error_code_available_v&lt;T&gt;</code></p>


        </div><p><small>Last revised: October 10, 2019 at 18:14:56 &#43;0100</small></p>
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